Familial aggregation in the night eating syndrome

Familial Aggregation in the Night Eating Syndrome
having an affected ﬁrst-degree relative
were signiﬁcantly greater than that of a
control proband (odds ratio ¼ 4.9, p <
drome (NES) affects ﬁrst-degree relatives
included in the model: proband bodymass index (BMI) (kg/m2), proband gen-
ﬁrst-degree relative gender, relationship
to proband (i.e., mother, father, or sib-
10 day sleep and food records, the Eating
(night eater or control); none was statisti-
tured Clinical Interview for DSM IV Axis I
ence of NES among ﬁrst-degree relatives.
A proband predictive model, using logis-tic regression analyses and the general-
Keywords: night eating syndrome; familial
correlation among observations withinfamilies was used to assess familialaggregation.
A ﬁrst step in understanding potential genetic
and environmental inﬂuences is a study of familial
The night eating syndrome (NES) is characterized
aggregation. Accordingly, the current study exam-
as a delay in the circadian pattern of food intake
ined the extent to which the NES phenotype affects
manifested by evening hyperphagia and/or noctur-
ﬁrst-degree relatives of both night eaters and con-
nal awakenings with ingestion of food.1,2 Night eat-
ers frequently report morning anorexia, insomnia,and negative mood that worsens during the eve-ning; the onset of NES is often associated with lifestress.3
The etiology of NES is unknown, but genetic
inﬂuences have been suspected. The response ofNES to sertraline4 suggests that genes regulating
serotonin gene may be involved. Additionally, a
Night eaters were recruited from printed advertise-
recent study found that mice with a mutation in
ment, radio talk shows, and television commercials
the Clock gene consume signiﬁcantly more food
describing NES. Controls, recruited from printed and
than wild-type mice during the light period (when
radio advertisements, were sought to approximate the
mice usually sleep more and eat less) and become
age, gender, body mass, and ethnicity of the night eaters.
Advertisements for both night eaters and controlsincluded the following eligibility requirements: age 18 orolder, not currently involved in an occupation requiring
nightshift work, not currently enrolled in a weight reduc-
*Correspondence to: Jennifer D. Lundgren, PhD, 3535 Market
tion program, and not currently taking any psychotropic
Street, Suite 3123, Philadelphia, PA 19104-3309.
medications. Advertisements to recruitment night eaters
University of Pennsylvania School of Medicine Weight and
speciﬁed that they must have difﬁculties with overeating
Eating Disorder Program, Philadelphia, Pennsylvania
after dinner and/or with waking up at night to eat; adver-
tisements for controls stated that they could not experi-
(www.interscience.wiley.com). DOI: 10.1002/eat.20269
International Journal of Eating Disorders 39:4 000–000 2006—DOI 10.1002/eat
Participants included 103 adults diagnosed with NES
(mean age ¼ 43.0 6 11.3 years; mean BMI ¼ 33.3 6 8.1
As part of a comprehensive study of the characterization
kg/m2; percentage white ¼ 62.1; percentage female ¼
of NES, NES and control participants provided informed
71.8) and 42 control participants (mean age ¼ 39.3 6
consent, completed the NEQ and the FHQ, and heights
11.3 years; mean BMI ¼ 36.0 6 6.2 kg/m2; percentage
and weights were measured. NES participants were inter-
white ¼ 59.5; percentage female ¼ 66.7). Night eater and
viewed using the NESHI to assess their NES symptoms.
control participants differed signiﬁcantly only on BMI
Both NES and control participants were interviewed with
(p ¼ .05); accordingly, proband BMI was included as a
the EDE and kept detailed 24-hour food records for 10 con-
secutive days to conﬁrm their diagnostic status.
Participants were diagnoses as ‘NES positive’ if they
met the following criteria based on food records and
NESHI interview: (1) consuming 25% of total daily calo-
The Night Eating Questionnaire (NEQ6) was used
ric intake after dinner, and/or (2) nocturnal awakenings
to assess the presence of night eating behavior. It is
with ingestion of food occurring 3 times/week. Partici-
comprised of 14 questions assessing hunger and craving
pants must have experienced symptoms for no less than
patterns throughout the day, percentage of calories
3 months based on self-report. This operational deﬁni-
ingested after suppertime, feelings of depression, insom-
tion was modiﬁed from previously described criteria1
nia and awakenings, and nocturnal food cravings and
because recent data with a larger sample of night eaters
and controls found that night eaters consumed 34.6% 6
The Night Eating Syndrome History and Inven-
10.1% of total daily caloric intake after dinner compared
tory (NESHI; unpublished semi-structured interview)
with controls who consumed 10.0% 6 6.9% of total daily
was used in conjunction with food records to establish
caloric intake after dinner.2 Based on a ﬁgure of 2 SD
a diagnosis of NES. The NESHI included questions
above the mean for controls, 25% of calories consumed
about the schedule and amount of food intake
after the evening meal was considered abnormally large.
throughout the 24-hour day, history of NES symptoms,
Participants who also met criteria for binge eating disor-
sleeping routine, mood symptoms and life stressors,
der (BED; NES, n ¼ 20; control, n ¼ 0) were retained in the
weight and diet history, and previous treatment strat-
analyses because the literature suggests that BED and NES
are two distinct conditions, although they may co-occur.9,10
The Eating Disorder Examination (EDE7) was used
to assess the presence of any concurrent eating disorder.
It is a semi-structured clinical interview that assesses
The proband predictive model described by Hudson
dietary restraint, eating concern, and weight and shape
et al.11 and Laird and Cuenco12 was used to predict the
concern, as well as bingeing and purging behaviors.
binary outcome (affected or not affected) of ﬁrst-degree
The Structured Clinical Interview for DSM IV Axis I
relatives. One logistic regression analysis was conducted,
Disorders (SCID I8) was used to formally assess the pres-
using the generalized estimating equation (GEE) with
ence of Axis I psychiatric diagnoses.
exchangeable correlation structure to control for correla-tion among the family members. Status as NES or control
Night eaters and controls completed detailed 24-hour
proband was used as the predictor; covariates in the
food records for 10 consecutive days. The ﬁrst two days
model were proband BMI, proband age, proband gender,
were practice days and day 10 did not include nighttime
proband ethnicity (white vs. non-white), ﬁrst-degree rel-
data. Accordingly, days 3–9 were used to conﬁrm a diag-
ative gender, ﬁrst-degree relative relationship to the pro-
nosis of NES. Food intake was analyzed using ESHA Food
band (mother, father, or sibling), and the interaction
between proband status (night eater or control) and ﬁrst-
A family history questionnaire (FHQ) was completed
degree relative relationship to the proband.
by NES and control probands to assess the presence ofNES among parents, siblings, and offspring. Probandresponses were compared with their self-report duringthe NESHI interview. When discrepancies were encoun-tered and when the probands were unsure about the
presence of NES, the ﬁrst-degree relative was coded‘unaffected.’
The ﬁrst-degree relatives of NES probands had sig-
BMI was calculated from height and weight measured
niﬁcantly greater odds of being affected with NES
at their interview visits. Normal weight was deﬁned as
than the ﬁrst-degree relatives of control probands
18.5–24.9 kg/m2, overweight was 25–29.9 kg/m2, and
(odds ratio [OR] ¼ 4.9; standard error [SE] ¼ 2.9;
95% conﬁdence interval [CI] ¼ 2.0, 12.3; p ¼ .0006).
International Journal of Eating Disorders 39:4 000–000 2006—DOI 10.1002/eat
FAMILIAL AGGREGATION IN THE NIGHT EATING SYNDROME
None of the covariates was statistically signiﬁcant
Despite these limitations, the study was able to
(all p values > .05) including proband BMI, pro-
show strong familial aggregation of NES; these results
band age, proband gender, proband ethnicity, ﬁrst-
highlight the need for a classic twin study of NES.
degree relative gender, relationship to proband(mother, father, or sibling), and the interaction
Support for this work was provided by NIH/NIDDK grant
between relationship to proband and proband sta-
RO1 DK 056735. Thanks go to Lindon Eaves, MA(Oxon),
PhD, DSc, Distinguished Professor of Human Geneticsand Psychiatry, Virginia Commonwealth UniversitySchool of Medicine, for his valuable feedback regardingthe statistical analyses. Thanks are also extended to Wei
Yang of the Center for Clinical Epidemiology and Biosta-
This is the ﬁrst study to examine the familial aggre-
tistics at the University of Pennsylvania School of Medi-
gation of NES. It found that NES was more likely to
cine for his assistance with the statistical analyses.
aggregate among family members of night eatersthan of controls, suggesting that NES is familial.Congruent with our ﬁndings, a recent study of
German children (5–6 years of age) and their moth-ers by Lamerz et al.13 found that the children of
1. Birketvedt GS, Florholmen J, Sundsfjord J, Osterud B, Dinges D,
mothers who engaged in night eating behavior
Bilker W, et al. Behavioral and neuroendocrine characteristicsof the night-eating syndrome. JAMA 1999;282:657–663.
were 7.8 times more likely than children of non-
2. O’Reardon JP, Ringel BL, Dinges DF, Allison KC, Rogers NL, Mar-
night-eating mothers to show signs of the syn-
tino NS, et al. Circadian eating and sleeping patterns in the
night eating syndrome. Obes Res 2004;12:1789–1796.
The strengths of the current study, in contrast to
3. Stunkard AJ, Grace WJ, Wolf HG. The night-eating syndrome: a
pattern of food intake among certain obese patients. Am J Med
the study carried out by Lamerz et al.,13 included the
use of an adult sample of probands, parents, and sib-
4. O’Reardon JP, Stunkard AJ, Allison KC. Clinical trial of sertraline
ling, diagnosis of probands using food and sleep
in the treatment of night eating syndrome. Int J Eat Disord
records in conjunction with clinical interview, and
robust statistical methods using the generalized esti-
5. Turek FW, Joshu C, Kohsaka A, Lin E, Ivanova G, McDearmon E,
et al. Obesity and metabolic syndrome in circadian clock
mating equation to control for correlated family data.
mutant mice. Science 2005;308:1043–1045.
Although 20 of the NES probands also met criteria
6. Allison KC, Stunkard AJ, Their SL. Overcoming night eating syn-
for BED, only seven of those concurrently diagnosed
drome: a step-by-step guide to breaking the cycle. Oakland,
reported a family history of NES. It is unlikely that
7. Fairburn CG, Cooper Z. The Eating Disorder Examination (12th
familial aggregation can be attributed to BED aggre-
ed). In: Fairburn CG, Wilson GT, editors. Binge eating: nature,
gation. Several NES probands, however, also met cri-
assessment, and treatment. New York: The Guilford Press, 1993,
teria for an Axis I disorder; co-aggregation of NES
and Axis I disorders (e.g., Major Depressive Disorder)
8. First MB, Spitzer RL, Gibbon M, Williams JBW. Structured Clini-
should be examined in future studies.
cal Interview for DSM-IV Axis I Disorders–Patient Edition (SCID-I/P with Psychotic Screen,
Although a ﬁrst step in understanding the etiol-
Department, New York State Psychiatric Institute; 1996.
ogy of NES, this study was limited in the following
9. Stunkard AJ, Berkowitz R, Wadden T, Tanrikut C, Reiss E, Young L.
ways. First, the family history method, rather than
Binge eating disorder and the night eating syndrome. Int J Obes
the family interview method, was used to assess
10. Napolitano MA, Head S, Babyak MA, Blumenthal JA. Binge eat-
night eating among ﬁrst-degree relatives. Because
ing disorder and night eating syndrome: psychological and
the limitations of the family history method are
behavioral characteristics. Int J Eat Disord 2001;30:193–203.
well documented,14 we sought, but we were unsuc-
11. Hudson JI, Laird NM, Betensky RA. Multivariate logistic regres-
cessful, in recruiting family members to participate
sion for familial aggregation of two disorders. I. Development
in veriﬁcation interviews. Second, some probands
of models and methods Am J Epidemiol 2001;153:500–505.
12. Laird NM, Cuenco KT. Regression methods for assessing familial
were unsure if family members were affected with
aggregation of disease. Statis Med 2003;22:1447–1455.
NES, and were, therefore, considered unaffected.
13. Lamerz A, Kuepper-Nybelen J, Bruning N, Wehle C, Trost-Brink-
Third, control probands may have been less likely
hues G, Brenner H, et al. Prevalence of obesity, binge eating,
to recognize NES among relatives compared with
and night eating in a cross-sectional ﬁeld survey of 6-year-old
NES probands, for which the disorder is more sali-
children and their parents in a German urban population. JChild Psychol Psychiatry 2005;46:385–393.
ent. Fourth, the study was nonblinded in that the
14. Roy MA, Walsh D, Kendler KS. Accuracies and inaccuracies of
interviewer knew the diagnosis of the proband at
the family history method: a multivariate approach. Acta Psy-
the time the family history was obtained.
International Journal of Eating Disorders 39:4 000–000 2006—DOI 10.1002/eat